What Is A French Drain? Your Guide From ’58 Foundations & Waterproofing

As a homeowner, dealing with a wet basement or a soggy yard after heavy rain can be a frustrating experience—especially when it leads to damaged belongings, mold growth, or a dead, muddy lawn. Fortunately, there’s a tried-and-true solution that can help keep your home and your landscaping dry: French drain systems.

If you’re wondering, “Why is it called a French drain?” the answer may surprise you. While the word “French” might evoke thoughts of eloquence, the truth is quite the opposite. Coined and popularized by Henry Flagg French in his book Farm Drainage (published in 1859), a French drain system features a sloped trench that is filled with gravel or rock and a perforated pipe. This system diverts surface water and groundwater away from a specific area—such as your foundation or an area with heavy landscaping—to designated areas like drainage ditches or a low-lying area of your property.

If you’re new to the concept of French drain systems, this guide is here to help. Below, we will uncover how a French drain works, different circumstances when you might need one, and how ’58 Foundations & Waterproofing can help.

When Do I Need a French Drain System?

Installing a French drain system can be beneficial if you’re constantly experiencing these problems after heavy rainfall:

  • A soggy lawn or area that regularly collects surface water
  • A leaky foundation that lets water or moisture into your basement

Depending upon which of these problems you’re experiencing, there are two different types of French drain systems that can help: outdoor French drain systems and indoor French drain systems.

Outdoor French Drain Systems

Diagram of a home with a view of an outdoor French drain system

The gutter system on your home collects rainfall from your roof and diverts that water away from your foundation. Similarly, an outdoor French drain system collects rainfall from the ground level to achieve the same goal. For example, if water pools in low spots throughout your yard, an outdoor French drain system would ensure this water drains and flows away to a designated area. Another example is if water is making its way through your foundation and into your basement. Rather than allowing groundwater to put hydrostatic pressure on your foundation and seep indoors, an outdoor French drain system can help to reroute that water away from your foundation.

The Downsides of Outdoor French Drain Systems

While outdoor French drain systems work well to funnel water away from low-lying areas in your yard, they aren’t a 100% effective or cost-efficient solution to fix a leaky or moisture-prone basement. When installing an outdoor French drain system to alleviate hydrostatic pressure around your foundation, you must remove a significant amount of the soil—as well as any decks, patios, driveways, or landscaping—that surrounds your foundation’s perimeter. This process typically requires heavy machinery and a great deal of labor, which can be extremely costly.

The drain lines of an outdoor French drain system can also clog with silt over time, which reduces their ability to eliminate water pressure against your foundation. And, when an outdoor system needs to be repaired or a clog needs to be removed, the whole system needs to be dug up and replaced, which puts you back to square one. For this reason, outdoor French drain system warranties are typically much shorter than other basement waterproofing solutions.

Indoor French Drain Systems

Diagram of an underground view of an indoor French drain system

To ensure a leaky or moisture-prone basement stays dry even after heavy rainfall, an interior French drain system should be installed. With an indoor French drain system, drainage channels and drain lines are installed along the perimeter of your basement floor—right where your basement floor meets the walls. These drain lines are then routed to a sump pit where a sump pump is installed. As water is routed from the drain lines into the sump pit, a float valve is triggered and turns on the sump pump. This type of indoor basement waterproofing solution actively works to push water out of your basement 24/7.

’58 Foundations & Waterproofing: Experts in Indoor French Drain Systems

At ’58 Foundations & Waterproofing, we’ve been in the business of waterproofing basements for more than 60 years. Compared to outdoor French drain systems, our interior basement waterproofing systems are much more cost-efficient and effective in the long run—and they do not require extensive digging around the exterior of your foundation.

For even more moisture prevention for homes with crawlspaces, we also provide industry-leading crawlspace encapsulation services. During the encapsulation process, our experienced team will seal all crawlspace vents, as well as seal the ground, walls, and support columns with a 20-millimeter-thick vapor barrier.

If your exterior French drain system isn’t keeping your basement dry, trust the basement waterproofing professionals at ’58 Foundations & Waterproofing. Get in touch with our team today to schedule your waterproofing inspection.